September 29, 2008- In the last days of 2007, President Bush signed the Energy Independence and Security Act of 2007, which mandated the automotive industry to raise its fleet-wide fuel economy average by 40 percent by 2020. This bill cracks open a world of opportunity for the aluminum industry, as one of the surest ways to greater fuel economy is the lightweighting of vehicles.
Plenty of payback
According to Buddy Stemple, vice president and general manager of Novelis Inc., Atlanta, and chairman of the automotive and light truck group at The Aluminum Association, Washington D.C., although the initial cost of replacing traditional building materials in cars with aluminum is slightly more expensive, it's offset by a number of positive effects.
"If you look at it from an up-front cost per pound, [aluminum] is expensive," says Stemple. "It's a little more expensive than traditional steel. But if you take into account the secondary weight savings that you can get by having a lighter structure and you look at the improved fuel economy that the consumer would get over the car's life cycle, it's cheaper to build a lightweight vehicle."
According to a recent study at The Aluminum Association, there are also savings incurred by the reduction of horsepower and torque requirements in an aluminum powertrain, which helps balance out initial material costs.
With high fuel prices, any relief a consumer can get at the pump is welcome. Some hybrids are said to pay back higher initial costs in as little as five years through savings at the pump, according to Stemple. Adding a lightweight aluminum structure can shave an additional year or more off that figure. "The real value with aluminum is: If you can take a car and reduce its mass, it takes less energy to move and it emits less greenhouse gases," says Stemple.
A safe bet
Although companies like Audi and Jaguar have developed all-aluminum-structured vehicles, North American automakers still favor heavier steels. However, that trend is changing. Eighteen percent of hoods on North American vehicles are aluminum, and aluminum trunks and fenders aren't uncommon.
Currently, the average vehicle contains 327 pounds of aluminum, but that figure has been increasing steadily for the past 33 years. Today, there are more than 80 models on the road built with at least 400 pounds of lightweight aluminum.
"The myth out there is that lighter isn't safe," says Stemple, citing the Jaguar XJ as a prime example of a larger, lighter aluminum-based vehicle getting high safety ratings. It's 400 pounds lighter and larger than the steel model it replaced, gets an additional 4 miles per gallon on the highway and received the top safety rating in its class by the insurance industry. "There's more room for crush zones, and aluminum is about twice as stiff, so it has quite a nice handling ride, and it absorbs more energy. You can put in a longer crumple zone, increase the safety and still maintain the size that we like here in North America."
With the number of advantages of using aluminum becoming more apparent, it appears the 33-year streak of the metal's increasing prominence in automotive manufacturing will continue well into the future.
"If you have a car that has less mass, then you can do things like downsize the powertrain and downsize the engine," says Stemple. "All those other technologies don't have to work as hard. And therefore, with some good engineering and design, the vehicle can be optimized in terms of cost and performance." MM